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Check with Charles Talbert at M-Series RebuildBoth are very close but the wires on my switch are tagged B, C, D, E, F, G. After poking around a little more I've found that page 2-70 of TM 9-2320-212-20 Organizational Maintenance Manual Nov 1973 diagrams a couple of switch variations one of which looks like it fits the Signal-Stat 600 that I have.
After opening my switch and comparing the internal wiring to the diagram it looks like the mapping is
B - M
C - C
D - D
E - A
F - F
G - H
Thanks for all of the help. Now I just need to find a relay box and a flasher unit. Any ideas?